Identification of new epitopes recognized by human monoclonal antibodies with neutralizing and antibody-dependent cellular cytotoxicity activities specific for human T cell leukemia virus type 1

M. Kuroki, M. Nakamura, Y. Itoyama, Y. Tanaka, H. Shiraki, E. Baba, T. Esaki, T. Tatsumoto, S. Nagafuchi, S. Nakano, Y. Niho

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We have generated a number of EBV-transformed B cell lines producing human mAb against human T cell leukemia virus type 1 (HTLV-1) from the peripheral blood B lymphocytes obtained from patients with HTLV-1-associated myelopathy/tropical spastic paraparesis. Various synthetic peptides corresponding to antigenic regions of HTLV-1 gag and env proteins were used for the screening of antibodies in ELISA. In our study, four IgG mAb to the gag p19 amino acids 100 to 130, and 5 IgG mAb to the env p46 amino acids 175 to 199 were characterized. An immunofluorescence assay showed that all of these mAb specifically bound to the surface of HTLV-1-bearing cell lines. Among these mAb, one anti-gp46 mAb, designated KE36-11, neutralized the infectivity of HTLV-1 as determined by both the inhibition of HTLV-1-induced syncytium formation and transformation assays in vitro. An antibody-binding assay using overlapping oligopeptides revealed that KE36-11 recognized a new epitope locating between the gp46 amino acid sequence 187-193 (Ala-Pro-Pro- Leu-Leu-Pro-His). Another anti-gp46 mAb, designated KE36-7, showed antibody- dependent cellular cytotoxicity against HTLV-1-bearing cell line. KE36-7 bound strongly to the 10-mer peptide-gp46 187-196, and weakly to peptides containing the gp46 amino acid sequence 191-196 (Leu-Pro-His-Ser-Asn-Leu). These two epitopes, which are associated with HTLV-1 neutralization and antibody-dependent cellular cytotoxicity, are thus the first epitopes identified in human HTLV-1 infection. It is possible that passive immunization of humans with these two human mAb are effective on the protection of HTLV-1 infection in vivo.

Original languageEnglish
Pages (from-to)940-948
Number of pages9
JournalJournal of Immunology
Issue number3
Publication statusPublished - Jan 1 1992


All Science Journal Classification (ASJC) codes

  • Immunology and Allergy
  • Immunology

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